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A gonad, sex gland, or reproductive gland [1] is a mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. [2] The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells
The development of the gonads is part of the prenatal development of the reproductive system and ultimately forms the testicles in males and the ovaries in females. The immature ova originate from cells from the dorsal endoderm of the yolk sac. Once they have reached the gonadal ridge they are called oogonia.
Male gonad (testes, left) and female gonad (ovaries, right) Males have two testicles of similar size contained within the scrotum, which is an extension of the abdominal wall. [1] Scrotal asymmetry, in which one testicle extends farther down into the scrotum than the other, is common. This is because of the differences in the vasculature's ...
Tail end of human embryo, from eight and a half to nine weeks old. 1 - 7: Homologous male and female pelvic organs. Diagrams that show the development of male and female organs from a common precursor.
The primary sex organs are the gonads, a pair of internal sex organs, which diverge into testicles following male development or into ovaries following female development. [8] As primary sex organs, gonads generate reproductive gametes containing inheritable DNA. They also produce most of the primary hormones that affect sexual development, and ...
This is the indifferent stage during which the gonads are relatively large and have an outer cortex of primitive sex cords and an inner medulla. [4] Specialized primordial germ cells are forming and migrating from the yolk sac to the embryonic gonads during week eight and nine. These are the spermatogonia in the developing male. Before seven ...
Gonadal development is a process, which is primarily controlled genetically by the chromosomal sex (XX or XY), which directs the formation of the gonad (ovary or testicle). [4] Differentiation of the gonads requires a tightly regulated cascade of genetic, molecular and morphogenic events. [5]
Hypogonadism means diminished functional activity of the gonads—the testicles or the ovaries—that may result in diminished production of sex hormones. Low androgen (e.g., testosterone) levels are referred to as hypoandrogenism and low estrogen (e.g., estradiol) as hypoestrogenism. These are responsible for the observed signs and symptoms in ...